Journal Article

Leaf-level photosynthetic capacity in lowland Amazonian and high-elevation Andean tropical moist forests of Peru

Nur H. A. Bahar, Alberto Escudero Vega, Judit Huaman Ovalle, Tomas F. Domingues, Roberta E. Martin, Lasantha K. Weerasinghe, Norma Salinas, F. Yoko Ishida, Rosalbina Butrón Loayza, Carlos A. Quesada, John R. Evans, Patrick Meir, Felipe Sinca, Jhon del Aguila-Pasquel, Yulina Pelaez Tapia, Owen K. Atkin, Odhran S. O’Sullivan, Benedict M. Long, Paola P. Zuloaga Ccorimanya, Katherine Quispe Huaypar, Oliver L. Phillips, Rossella Guerrieri, Israel Cuba Torres, Eric G. Cosio, Jon Lloyd, Yadvinder Malhi, Keith J. Bloomfield, Gregory P. Asner

2017

Overview

We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests (TMFs) in the Andes/western Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco (V cmax), and the maximum rate of electron transport (J max)), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area (M a, Na and Pa, respectively), and chlorophyll from 210 species at 18 field sites along a 3300-m elevation gradient. Western blots were used to quantify the abundance of the CO2-fixing enzyme Rubisco. Area- and N-based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMFs, underpinned by greater investment of N in photosynthesis in high-elevation trees. Soil [P] and leaf Pa were key explanatory factors for models of area-based V cmax and J max but did not account for variations in photosynthetic N-use efficiency. At any given Na and Pa, the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil- and leaf-P in defining the photosynthetic capacity of TMFs, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N-use efficiency of these critically important forests.

• Publisher: New Phytologist Trust,Wiley Subscription Services, Inc
• Subject: Altitude / Amazonia / Andes region / Area / Capacity / Carbon dioxide / Carbon Dioxide - metabolism / Carboxylation / carboxylation capacity / Chlorophyll / electron transfer / Electron transport / Elevation / Enzyme Assays / Forests / highlands / Humidity / Kinetics / Leaf area / leaf traits / Leaves / Models, Biological / Nitrogen / nitrogen (N) / Nitrogen - metabolism / nutrient use efficiency / Peru / Phosphorus / phosphorus (P) / Photosynthesis / Photosynthesis - physiology / Plant Leaves - anatomy & histology / Plant Leaves - chemistry / Plant Leaves - physiology / ribulose bisphosphate regeneration / Ribulose-bisphosphate carboxylase / Ribulose-Bisphosphate Carboxylase - metabolism / Soil / Species Specificity / Temperature / Trees / Tropical Climate / Tropical forests / tropical rain forests / Variation / Western blotting